(Flow soldering method)

Please read these instructions all the way through first, before starting to build our frogs.
***WORK IN PROGRESS***Br> - Pictures will be added as they become available.


The frog kits can be heated until the solder paste flows with any of three heating methods.

1) Dry, High Wattage Soldering Iron
750-800 deg F

2) Soldering Capable Hot Air Gun 750 deg F

3) Resistance Soldering Unit
(with the heat shield removed)

A short plain wide-bladed standard screw driver for use as a hold-down probe.

A Dremel type hand held miniature drill with #409 fine abrasive cutting disks.

A completely flat fine abrasive pad for a tarnish removing surface, is recommended for cleaning the frog kit fret.

An electronics rosin past flux is recommended for solder-free fluxing of the center web section of the frog.

Ultra fine printing industrial electronic solder paste as supplied by the stores

A supply of thin nitrile or vinyl protective examination style gloves for keeping hands clean while printing the solder paste

Consumables such as hard felt printing pads and replacement heat shield strips can be supplied by the Stores.


The metal jig strip, with the heat shield, arranged so the holes are the same way around, placed on top, can be fixed down together onto a convenient bench surface with the two #6 screws provided. If you are using a resistance soldering unit, leave off the heat shield and fasten the RS unit ground lead to the 8-32 tapped hole with the included brass screw and washer. Place two of the dowels in the appropriate jig holes ready for use. Keep the remaining spare dowels in case you need them later.


Peel off the backing of the self adhesive felt pad strips and stick them equally spaced inside the base of the box as shown. Use the pad on one far side for solder paste and the the pad on the other far side for flux paste. The center pad may be used for an optionala degreasing solvent, such as alcohol, if desired.

Before touching any solder paste items, and at the start of every new soldering session, we strongly advise that you put on a fresh pair of light disposable nitrile-type industrial gloves. These are intended to help prevent your hands from becoming soiled with the extremely finely powdered solder paste, while applying it. Our solder paste is lead free, but should still be treated as a toxic substance and only handled with the necessary appropriate safety precautions. Wash hands and finger nails thoroughly after each soldering session. Keep paste or any pasted items away from food, children and small animals. Also stop and wash hands and replace any glove that becomes punctured during a session.

Prepare the solder pad by running a single continuous line of solder paste from the opened syringe nozzle the full length of the pad. Replace the syringe nozzle plug firmly, then spread the paste evenly over the whole pad with a small flat ended metal spatula.

Do the same to the flux pad with paste flux, with a separate spatula. Do not let any solder paste get onto the flux pad. Stop and clean off any that gets there by accident. A square inch or so of paper towel will usually work for cleaning off small amounts.

Test the initial amount of solder paste on the solder pad is sufficient by pressing a frog section, or small piece of flat scrap metal down onto it and observing the amount of paste that transfers to it. The ideal amount will strongly color the metal gray while still appearing very slightly speckled, with a tinge of the metal color showing through. A caked solid paste layer is too much and a light dotted appearance is too little. The pictures to be added later show these levels as examples.

In normal use, you can expect the pad material to apply close to the correct amount automatically.

Only if the initial application to a new pad tests as too little the first time, then add a second line of paste and re-spread it and repeat. In general, once the solder pad has been has been used, one application of paste will print around 5-7 frog kits and adding a single line of paste spread flat each time, will replenish it for another 5-7 frogs, and so on.


Place the frog kit on the bench the same way up as shown above. This is the TOP SIDE of the kit. Familiarize yourself with the kit parts in place. A code 70 or code 83 frog kit will have three long horizontal framed sections as above. A code 55 kit will just have the lower two sections. Two thinner metal tabs (seen between the large holes) hold each section to the next.

Each section has a rectangular pad with an alignment hole at each end. The two outer thin strips of metal between the pads form a delicate, but fairly rigid, frame around each section and prevent the inner frog parts proper from becoming distorted during shipment and assembly. When handling, always hold the sections only by the alignment pads, to prevent any distortion or damage to the frame. The inner frog parts must not be removed from the frames until the assembly process is complete.

For HO 88-SAFE frogs be especially careful not to pull outward or twist the separate "vee" portion. It must be kept properly flat and central before and during assembly. BE AWARE THE VEE HAS A VERY SHARP POINT, SO TAKE SPECIAL CARE WHEN HANDLING, TO NOT INJURE YOURSELF>

The lowest section in the picture is the frog base. The underside of the base (which usually has the frog size and/or writing on it) is actually upside down as supplied in the kit. This section will have to be turned over later during assembly.

The next section up is the frog top and is the correct way up as shown.

The very top section, if provided, is the center (rail web) portion of the frog and can be used either way up.

It is normal for the frog kit to be slightly bowed from left to right. This caused by the manufacturing process and not by shipping. However if any of the frames are significantly bent or otherwise damaged, contact us for advice BEFORE attempting to assemble the frog kit.


We strongly recommend cleaning any tarnish from the UNDERSIDE of the frog by rubbing it lightly on a flat abrasive pad, before separating the parts. For code 70 and 83 kits, you can turn the kit over and using the edge of the abrasive block, clean JUST the WEB section in the same manner. Suitable inexpensive fine diamond dust coated flat pads are available from good hardware or tool stores. At this point it is a good time to just check that the alignment holes are not too tight or slightly blocked. Run a hand held (1/8" for HO) twist drill through all the holes to make sure they are a freely sliding fit, to ensure the parts do not jam on the fixture dowels later.

With the tarnish cleaned, the kit sections can now be cut apart.

Hold down the kit on flat expendable surface and using a firmly held Dremel with a thin (#409 - 0.025 in. thck ) cut-off disc ( and proper eye protection! ) or a fine razor saw, carefully separate the kit horizontally into the individual separate sections, by cutting through the two tabs between the sections.

These are the sections after they have been separated. The base is still shown upside down.


Wearing the gloves and using the prepared pad box, press the frog kit top section firmly onto the solder pad to print solder onto its underside. Pay careful attention to placing enough solder paste onto rail ends and the wing rails right to their ends. You can usually make the printing denser at the pressure point by slightly rotating or sliding the section while on the pad.

For a code 70 or 83 frog, print just flux onto both sides of the center section, and then print solder onto the upper side of the base section. (Note: for a code 55 frog, print just flux onto the upper side of the base section)

Here we see the almost ideal result of printing solder paste on the inner surfaces. The speckled effect may be a little denser, especially on the thin wing rails, but it does not need to be completely solid gray, and there should be no thick caking anywhere. If in doubt, you can always wipe the parts clean again, using a small piece of kitchen roll and repeat the printing until you have it right. Also before completion, wipe off any surplus paste that may have gotten into any of the open spaces or the top surface/flange ways. Otherwise these will melt and blob on the rails, flange ways or outside and be unsightly or even block the flange ways.

Once the printing is finished satisfactorily, then place the frog sections in the correct order on the two dowels set into the fixture base and push down. THE ACTUAL SOLDERING PROCESS

Using your chosen heating device, first heat the large end alignment hole tab at the narrow (toe) end of the frog. This prevents the end metal acting as a cold heat sink. Press the hold down tool down firmly about 1/4" into that end of the frog. Watch for the solder edges of the solder paste at the rail end tabs turning silver, then keep the hold down blade about 1/4" ahead of the heat and move both slowly along the frog, keeping up with the flow of the turning silver locations underneath. Make sure particularly the ends of the wing rails are each pressed firmly down with solder melting underneath them before moving onto the rails at the other end of the frog. Finally move the heat and hold-down onto the the other end alignment tab, and let the solder cool while still holding down firmly.

NOTE: the frog, fixture and dowels are all very hot at this point. Leave all to cool down sufficiently before lifing the frog off the fixture. Take care not to catch and tear up the heat shield during the removal, especially if the dowels lift with the frog.

When cool enough to hold, the frog can be readied to be cut from from its frame and cleaned up for final use.

In the case of the "88 safe" style frogs, the side frame should be cut through very carefully first in order to then move accross further to gently sever the long tabs attached to the wing rail tips. I do this by using a firmly held Dremel with the thin cutoff wheel (and eye protection) in one hand and the still framed frog in the other hand. Note: Do NOT use excessive force, or use other than very very short quick single dremel strokes at a time, as cutting for any longer than a momentary stroke will can easily cause the tiny metal pieces to instantly bend or their solder joints to melt or break, or both.

Only whe the wing rail tabs have been cut, then move on to cutting the end rail tabs and removing the remaining two halves of the frame. The frame is no longer needed so it does not matter if that is cut or breaks into more pieces. Again do not use any excessive force, or use other than quick single dremel strokes at a time, as the end rail joints are also susceptible to OVERHEATING while cutting.

Congratulations! You now have a completed frog. Carefully clean up any excess solder and/or past/flux. Rinsing in alcohol and brushing with an old tooth brush is good for clean up. Any excess solder or blobs can usually be smoothed or removed by GENTLE application of a Dremel spinning wire brush. Please remember, even though assembled, this frog is still a delicate, precision, fine scale component and should always be handled with reasonable care to prevent damage or distortion.<

For finishing, we recommend a chemical blackener such as "Blacken-it" if you wish to darken the inside of the flangeway. Painting the inside of the flangeway is not recommended and can affect both electrical and mechanical reliable operation. Painting and super-detailing the outside of the frog is, of course, no problem.